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DIGITAL HALFTONE SCREEN WITH 64 OUTPUT LEVELS IN AN 8X8 MATRIX

IP.com Disclosure Number: IPCOM000026214D
Original Publication Date: 1990-Oct-31
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 62K

Publishing Venue

Xerox Disclosure Journal

Abstract

The figure is an example of a 64 level digital halftone screen in an 8x8 matrix, The screen is to be applied to six bit (64 level) gray image input data to yield binary (2 level) image output data. The screen allows 64 different fractional area coverages given 64 level gray input image data. The screen also provides this level correlation with a perceived dot frequency of a 4x8 32 level digital halftone screen. The effect is achieved by repeating the dot growth pattern in the first half of the screen, then adding one to all of the screen elements in the second half of the screen. The commercial value of the screen lies in its ability to eliminate quantization errors which otherwise would occur in the translation between six bit gray and binary gray fractional area coverages.

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XEROX DISCLOSURE JOURNAL

DIGITAL HALFTONE SCREEN WITH 64 OUTPUT LEVELS IN AN 8x8 MATRIX
Paul M. Butterfield

Proposed Classification

U.S. C1.358/456 Int. C1. H04n 1/40

38

54

46

32

25

43 09

17

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44

62

58

48

19

01

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15

42 08
50 16
34 30
27 39

21 55

13 47
29
33

Figure

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DIGITAL HALFTONE SCREEN WITH 64 OUTPUT LEVELS IN AN 8x8 MATRIX(Cont'd)

The figure is an example of a 64 level digital halftone screen in an 8x8 matrix, The screen is to be applied to six bit (64 level) gray image input data to yield binary (2 level) image output data. The screen allows 64 different fractional area coverages given 64 level gray input image data. The screen also provides this level correlation with a perceived dot frequency of a 4x8 32 level digital halftone screen. The effect is achieved by repeating the dot growth pattern in the first half of the screen, then adding one to all of the screen elements in the second half of the screen. The commercial value of the screen lies in its ability to eliminate quantization errors which otherwise would occur in the translation between six bit gray and binary gray fractional area coverages.

380 XEROX DISCLOSURE JOURNAL Vol. 15 No. 5 September/October 1990

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